1. Field of the Invention
Embodiments of the invention are directed to preferentially delivering therapeutic gas to a patient. More particularly, the embodiments are directed to delivering therapeutic gas to one, a combination, or all of a patient's left naris, right naris and mouth selectively.
2. Background of the Invention
Patients with respiratory ailments may be required to breathe a therapeutic gas, such as oxygen. The therapeutic gas may be delivered to the patient from a therapeutic gas source by way of a nasal cannula.
Delivery of therapeutic gas to a patient may be continuous, or in a conserve mode. In continuous delivery, the therapeutic gas may be supplied at a constant flow throughout the patient's breathing cycle. A significant portion of the therapeutic gas provided in continuous delivery is wasted, i.e. the therapeutic gas delivered during exhalation of the patient is lost to atmosphere. In order to overcome the wastefulness of continuous delivery, related art devices may operate in conserve mode using a conserver system.
A conserver may be a device which senses a patient's inspiration, and delivers a bolus of therapeutic gas only during inspiration. By delivering therapeutic gas only during inspiration, the amount of therapeutic gas lost to atmosphere may be reduced. Conserver systems of the related art may sense a patient's inspiration at one naris and delivery the bolus of therapeutic gas to the other naris, such as through a bifurcated nasal cannula. Alternatively, conserver devices of the related art may sense a patient's inspiration at the nares generally, and delivery a bolus of therapeutic gas to the nares generally, such as through a non-bifurcated (single lumen) nasal cannula.
Sensing at one naris and delivering to a second naris may not work properly in all situations. If the patient has a blocked naris, e.g. because of congestion or some physical abnormality, either the sensing may not operate properly or the delivery of therapeutic gas may be to the blocked naris. Sensing and/or delivery may also fail to operate properly if the nasal cannula becomes dislodged, such as during sleep. Even if a nasal cannula stays properly on the patient and neither naris is blocked, delivering the patient's entire prescription of therapeutic gas through a single naris may cause nasal irritation.
When sensing inspiration by monitoring both nares simultaneously, congestion and/or abnormalities in the nares may cause the system to not sense properly. Moreover, when delivering therapeutic gas to the nares generally, such as through a single lumen cannula, congestion and/or physical abnormalities of the nares may affect the volume inhaled in each naris, wasting therapeutic gas in some cases and not providing sufficient therapeutic gas in other cases.